Laser Direct Structuring (LDS) is a process that enables an injection molded article to be selectively plated with metal to form discrete conductive circuit paths. First, a plastic article is injection molded using a polymer compound formulated specifically for this process. The article is then activated with a laser in the desired pattern, thereby activating the surface of the article in the areas traced with the laser. The article then undergoes an electroless plating process with a metal such as copper, nickel or gold; with the resultant circuit paths conforming exactly to the laser pattern.
The advantage of the Laser Direct Structuring (LDS) process is the ability to have a circuit path following the contour of the injection molded article, thus applying a true 3D circuit path. By integrating the circuit directly onto the plastic article, the designer now has freedoms previously unavailable. These design freedoms allow article consolidation, weight reduction, miniaturization, reduced assembly time, improved reliability and overall system cost reduction.
Key markets and applications for the Laser Direct Structuring process include medical, automotive, aerospace, military, RF antennas, sensors, security housings and connectors.
US20090292051 (SABIC) discloses a high dielectric constant thermoplastic composition that is capable of being used in a laser direct structuring process. The composition includes a thermoplastic base resin, a laser direct structuring additive, and at least one kind of ceramic filler. The thermoplastic composition comprises:
a) from 10-90% by weight of a thermoplastic base resin;
b) from 0.1-30% by weight of a laser direct structuring additive; and
c) 10-80% or less by weight of at least one ceramic filler;
                wherein the thermoplastic compositions are capable of being plated after being activated using a laser.        
The composition provides a high dielectric constant, low loss tangent thermoplastic composition. Copper chromium oxide spinel is used as the direct structuring additive.
US2012/0279764 (SABIC) discloses a thermoplastic composition that is capable of being used in a laser direct structuring process to provide enhanced plating performance and good mechanical properties. The compositions of that invention include a thermoplastic base resin, a laser direct structuring additive and a white pigment.
The thermoplastic composition comprises:
a) from 65-92% by weight of a thermoplastic base resin;
b) from 0.5-20% by weight of a laser direct structuring additive; and
c) from 0.5-15% by weight of at least one pigment selected from TiO2 including anatise, rutile, coated and uncoated, ZnO, BaSO4, CaCO3, BaTiO3 or a combination including at least one of the foregoing pigments;
                wherein the thermoplastic compositions are capable of being plated after being activated using a laser;        the laser direct structuring additive is a heavy metal mixture oxide spinel, such as copper chromium oxide spine; a copper salt, such as copper hydroxide, copper phosphate, copper sulfate, cuprous thiocyanate; or a combination including at least one of the foregoing laser direct structuring additives.        
US 20040241422 (LPKF) discloses a method to produce conductive tracks disposed on an electrically non-conductive support material by depositing a metallized layer on metal nuclei produced by using electromagnetic radiation to break up electrically non-conductive metal compounds dispersed in the support material, and a method for producing them. The electrically non-conductive metal compounds are insoluble spinel-based inorganic oxides which are thermally stable and are stable in acidic or alkaline metallization baths, and which are higher oxides which are thermally stable and are stable in acidic or alkaline metallization baths, and which are higher oxides with a spinel structure, and which remain unchanged in non-irradiated areas. The spinel based inorganic oxides used are heat resistant and remain stable after being subjected to soldering temperatures. The conductor tracks are reliably and easily produced and adhere strongly to the support.
US20080015320 (DU-PONT) discloses a light-activatable polymer composition including a polymer binder being present in an amount from 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96 or 97 weight percent of the total weight of the polymer composition; a spinel crystal filler present in an amount from 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 weight-percent of the total weight of the polymer composition, and methods for making same. In the examples of this application, CuCr2O4 is used as spinel.
In the prior art, based on LPKF technology, CuCr2O4 spinel is used as a laser direct structuring additive to enable the matrix resin to be used in a laser direct structuring process. One disadvantage of using CuCr2O4 spinel as a LDS additive is that CuCr2O4 spinel is detrimental to the mechanical properties of the matrix polymer. Thus the application of the resulting polymer will be limited. On the other hand it has been observed that a spinel such as NiFe2O4 cannot be plated at all and is bad in mechanical properties as well. In the present application, CuCr2O4 is replaced by another additive Ni—Zn ferrite (NiFe2O4 doped with ZnFe2O4) to obtain a thermoplastic polymer composition which is capable of being plated after being activated using a laser. Compared to the composition using CuCr2O4 spinel as a LDS additive, the mechanical property of the resulting composition of present application is improved.